Seattle, WA Development Impact Fees (2026)

SEATTLE DOES NOT CHARGE IMPACT FEES. The City of Seattle has not adopted any RCW 82.02 impact fees, so there are NO transportation/road, parks, fire, police, library, or open-space impact fees, and NO school impact fee. (Seattle Public Schools does not levy a school impact fee within city limits; the King County school-impact-fee program applies only to unincorporated King County and other cities, not Seattle.) A transportation impact fee has been studied/proposed since ~2014 but as of mid-2026 remains unadopted and tied up in SEPA litigation (DNS appealed by the Seattle Mobility Coalition; remanded 2019, reissued 2023, still not adopted). Confirmed via MRSC Impact Fees topic page (general WA authority) and web search corroboration of Seattle's non-adoption. INSTEAD OF IMPACT FEES, Seattle uses the Mandatory Housing Affordability (MHA) program (SMC 23.58C / MHA-R for residential) — an affordable-housing developer contribution. MHA is NOT a flat per-dwelling-unit fee and is NOT included as a per-unit row here because: (1) it applies ONLY to property that has been rezoned with an MHA suffix (M)/(M1)/(M2) (or certain zones where MHA is effective), not to ordinary single-family lots; and (2) the payment is calculated on total gross residential floor area times a per-square-foot "payment calculation amount" that varies by MHA area (low/medium/high) and is CPI-adjusted. SDCI Tip #257 confirms illustrative per-sf amounts in worked examples — e.g., a medium MHA area (NC3-55 (M1)) at $20.001/sf and a high MHA area (LR3 (M2)) at $37.961/sf — but the binding current per-sf table is "Exhibit E" attached to the Tip and is keyed to specific zones; a clean verbatim current table was not extracted, so MHA is reported as a caveat rather than a fee row. WHAT A RESIDENTIAL BUILDER ACTUALLY PAYS (verified, current): 1) Seattle Public Utilities System Development Charges (SDCs), the official adopted schedule effective 1/1/2026. These replace the prior water-only SDC. For a standard residential 3/4-inch meter: Water SDC $6,900 + new Wastewater SDC $2,600 = $9,500. These are additive (both apply to a new single-family connection). Larger meter sizes scale up (1-inch = $11,730 water + $4,420 wastewater = $16,150) and are included as excludeFromTotal rows. Wastewater and Drainage SDCs are ONLY charged inside the City of Seattle. Credit is given for existing water/wastewater service or hard surface; wastewater SDC is not charged for irrigation/fire-only services. 2) Drainage SDC: $1,225 per 1,000 sq ft of NEW hard surface (new in 2026, Seattle-only). Charged on increase in hard surface; included as a per_1000_sqft row (not in the per-unit total since it depends on impervious area). 3) King County Wastewater Treatment Division Capacity Charge — a SEPARATE regional charge levied by King County (not the City). Seattle's sewage is treated by King County's regional system, so new connections inside Seattle pay it. 2026 rate = $77.99 per Residential Customer Equivalent (RCE) per month, billed quarterly over 15 years (a medium single-family home = 1.0 RCE = $77.99/mo). A discounted lump-sum payoff is available but King County does not publish the figure (must contact King County). Reported as a monthly per-RCE charge; the 15-year obligation makes the effective lump-sum cost roughly ~$10,000-$13,000 per SFH but the exact lump sum is not published.

Caveats

SPU SDC amounts are the 1/1/2026 schedule (current, verified against the official PDF). Water service invoices issued on/before 12/31/2025 used the old water-only SDC. MHA per-sf amounts shown are illustrative example figures from Tip #257, not the binding current Exhibit E table. King County capacity-charge lump-sum total is not published.

Verify

confirmed 5 of 5 fee rows; dropped 0. All SDC figures (Water/Wastewater 3/4" $6,900/$2,600/$9,500; 1" $11,730/$4,420/$16,150; Drainage $1,225/1,000 sqft) matched the official SPU 1/1/2026 SDC PDF (sourceIndex 0) verbatim. King County capacity charge $77.99/RCE/month confirmed verbatim against the King County capacity-charge "about" page (sourceIndex 2). MHA Tip #257 (sourceIndex 6) confirmed: Exhibit E, $20.001/sf medium and $37.961/sf high examples present; MHA correctly kept as caveat, not a row. excludeFromTotal corrections: none — all flags correct: the two 3/4" SDC rows (Water $6,900 + Wastewater $2,600 = $9,500) are the only rows included in the representative per-dwelling-unit total (additive, no double-counting); Drainage (impervious-area-dependent), the 1" meter variant (non-representative meter size), and the King County recurring 15-year capacity charge are all correctly excludeFromTotal=true.

Dead/unused sources

sourceIndex 5 (Seattle OPCD Impact Fees page) returns HTTP 404 and sourceIndex 3 (2026 KC capacity-charge brochure PDF) returns HTTP 404 — neither underpins any surviving fee row (the capacity-charge row cites sourceIndex 2, which is live and confirms the figure), so no row was dropped; these citations should be repaired or removed.